Indicating means for automatic heeadlight dimming system



May 22, 1956 F. K. FOLAND 2,747,139

INDICATING MEANS FOR AUTOMATIC HEADLIGHT DIMMING SYSTEM ETAL 2 Sheets-Sheet 1 Filed Oct. 4, 1952 Inventors '5 275/0 May 22,- 1956 F. K. FOLAND ET AL INDICATING MEANS FOR AUTOMATIC HEADLIGHT DIMMING SYSTEM 2 Sheets-Sheet 2 Filed Oct. 4, 1952 Inventors INDECATING MEANS FOR AUTOMATIC HEADLKGHT DID/[MING SYSTEM Francis K. Foland, Elwood, and George W. Onlrsen and iilarold E. Todd, Anderson, Ind., assignors to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application Gctober 4, 1952, Serial No. 313,156

4 Claims. (Cl. 315-83) This invention relates to composite headlamp control systems for vehicles and more particularly to means for indicating the operating condition of the system. Current headlamp control systems utilize both a conventional foot dimmer switch and an automatic light actuated system for controlling the energization of either the bright or dim filaments. Unless some indicating means is provided to advise the driver as to which system is in control, he would not know whether it was necessary for him to operate a switch to dim the headlights or whether they would be dimmed automatically.

It is therefore an object in making this invention to provide indicating means for multiple control systems for multi-filament headlamps.

it is a further object to provide indicating means in a multiple control headlight system to indicate which system is operating for switching headlamp filaments.

it is a still further object to provide indicating means to advise an operator whether switching means for con trolling the energization of bright and dim headlamp fila ments is under manual or automatic control.

With these and other objects in view which will become apparent as the specification proceeds, our invention will be best understood by reference to the following specification and claims and the illustrations in the accompanying drawings, in which:

Figure l is a circuit diagram of a multi-filament headlight control system embodying the invention; and

Figure 2 is a circuit diagram of a modified form of control system embodying the invention;

Figure 3 is a partial circuit diagram illustrating an alternative location for the indicating lamp in the main circuit of Figure 2.

Referring now more particularly to Figure 1, there is shown therein a contact 2 labelled Upper which is adapted to be connected to the filaments of a headlight supplying the bright or upper beam. A second contact 4 labelled Lower is adapted to be connected to the filament supplying the shorter range or lower beam. Contact 2 is connected through line 6 with a stationary contact 8 of a single pole double throw switch having a second stationary contact 10 in spaced position to contact 8, the latter being connected through line 12 to contact 4. A movable switch arm 14 oscillates between these two stationary contacts 8 and 10, is spring biased toward its upper position by spring 16 and is pulled down into engagement with contact 111 by an electro-magnetic coil 18.

The movable switch arm 14 is connected through line 2%) to a second movable switch arm 22 of a single pole double throw switch 24. This latter switch is a conventional foot dimmer switch normally found in automotive vehicles. The movable arm 22 alternately engages stationary contact 26 and stationary contact 28 on each operation. Stationary contact 26 is connected through line 30 to a small indicating lamp 32, the opposite terminal of which is connected to ground. Stationary contact 2 8 is connected through line 34 to relay coil 18, the opposite terminal of which is connected to ground. A tie line 36 States Patent extends between line 34 and stationary relay contact 38 of the sensitive control relay 40. Line 46, connected to line 20, extends to the conventional 6-volt battery available in automotive vehicles.

Thus far the description has dealt with the main supply lines to the upper and lower filaments of a conventional lighting system in combination with the conventional foot switch and relay control. The automatic system for controlling headlamps due to the amount of light impinging on the forward portion of the vehicle consists in the main of two portions. One portion is the pickup or light sensitive unit indicated within the small dotted rectangle 42 in the upper right portion of Figure 1 and the second the power supply, amplifier and sensitive control relay unit outlined in a much larger dotted rectangle 44. It is obvious that there are various types of automatic headlight control systems that could be utilized and it is desired to point out at this time that the present automatic conrol system is shown for purposes of illustration, and not in any limiting sense.

Voltage is supplied to the power supply portion through line 142 directly connected to line 20. A fuse 149 is connected to the remote end of line 142 and to a line 7 0 which in turn extends to one terminal of a current regulating member 48, the opposite terminal of which is directly connected to the primary 5! of a power transformer 52. A vibrator unit 54 is connected across the primary in a conventional manner, causing alternate energizations of each of the two halves and inducing alternating currents in two secondaries 56 and 58 of the transformer 52. The secondary 56 is a high voltage secondary, in this instance providing some 1100 volts for the light sensitive element, which in this case is a photomultiplier tube. One terminal of the secondary 56 is connected through line 69 to the anode 62 of a diode rectifier 64, the cathode 66 of which is connected to ground. A filament 68 for the diode has one terminal grounded and the opposite terminal connected through line 70, fuse 140, line 142, to the 6-volt supply line 46. The opposite side of the secondary is connected through a line 72 to a plurality of resistors 74, 76 and 78 in series, which provide a potentiometer for power for the photomultiplier tube. A filtering condenser 80 is connected between line 72 and ground.

Resistor 74 has an adjustable tap 82 in engagement therewith, the latter being connected through line 84 to a variable potentiometer 86. The adjustable tap 88 of potentiometer 86 is connected to one end of a series of resistors 90 which supply varying voltages to the dynodes of the photomultiplier tube 92. The anode 94 of the photomultiplier tube 92 is connected through line 96 to one terminal of a fixed resistor 98, the opposite terminal being connected through line 109 with one terminal of a second fixed resistor 102, and the opposite terminal of the latter, in turn, being connected to a potentiometer 194. The variable tap 106 of potentiometer 104 is connected by line 108 to the 6-volt supply line 70. Line 70 is also connected through tie line 116 to one side of the second secondary winding 58, the opposite side of which is connected through line 112 to relay coil 114 of the sensitive control relay 40. The opposite side of said sensitive relay is connected through line 116 to the two plates 118 and 120 of the double triode tube 122. The control grid 124 of the first section of the tube is connected through line 126 to the anode output line of photomultiplier tube, line 96.

A smoothing condenser 128 is connected directly across the relay coil 114. A condenser 130 is connected between line 70 and line 100 and a tie line 132 is connected between line 100 and stationary contact 133 of the relay 40. The oscillating armature 134 of the relay 40 is connected through line 136 to one terminal of a fuse 138, the op posits terminal of which is connected to line 70. The grid 3 144 of the second triode section of the tube 122 is connected to the cathode of that section to form a diode and also through line 146 to stationary contact 148 of overriding switch 150, the movable portion 152 of the latter being connected to ground.

In the operation of this system it will be obvious that when the line 46 is connected to a source of power, such as a battery, when the headlight switch of the car is closed, there is a direct circuit to the upper headlight beams when the various switches are in the position shown. This circuit is as follows: line 46, line 20, armature 14, contact 8, line 6, and contact 2, which is connected to the upper filaments. Thus, as long as the conventional foot switch 24 remains in the position shown, the lights will be on upper beam, and the relay 18 is connected in circuit with the automatic system, and if energized thereby, will cause the lights to be switched to low beam or dim. This action is as follows: assuming that the vibrator power supply has produced the proper voltage across the potentiometer 74, 76, 78 for the photomultiplier tube 92, and the secondary coil 58 has supplied proper power for the energization of relay 40, the contact armature 134 will assume the left-hand position, as shown when no light falls on the photomultiplier tube. Under these conditions the control grid 124 of the first triode section of the tube 122 is at a relatively high potential and the tube is conducting through this portion to energize the relay coil 114. Upon the impingement of a predetermined amount of light on the pickup unit or photomultiplier tube 92, current will begin to flow in its output line 96, thereby reducing the potential at grid 124 until at a given point the first triode section will cease to conduct a suflicient amount of current to supply the relay coil 114 with sufficient energy to hold the armature 134 against its biasing spring 154 and the said spring will then move the armature over into contact wim stationary contact 38.

This will complete an energizing circuit for the relay coil 18 as follows: supply line 46, line 142, fuse 140, line 70, fuse 138, line 136, armature 134, contact 38, line 36, line 34, coil 18 to ground. This will cause the coil 18 to attract its armature 14, pulling it down into contact with stationary contact 10 to break circuit with the upper beam line and complete a circuit to the lower beam filaments. This will automatically, therefore, switch from high to low beam upon the impingement of a sufficient amount of light. When the approaching light source has passed or disappeared, current flow through the photomultiplier tube 92 will be diminished, the voltage on grid 124 will increase to a point where the first triode section of this tube will conduct enough current to cause relay coil 114 to again attract its contact 134 against spring pressure 154 and the supply circuit to coil 18 will be broken, permitting spring 16 to return armature 14 to its upper position, thereby deenergizing the lower beams and reenergizing the high or upper beam filaments. This action will continue as long as the switches are in the positions shown.

If it is desired to at any time override the automatic control system to bring the lights back to upper beam when the automatic system tends to maintain them on lower beam on the approach of a vehicle, this can be accomplished by closing override switch 150. It is to be recalled that when the automatic system switched to low beam, current flow through the first section of tube 122 was reduced to such a point that there was insufficient force in the relay 40 to maintain its contact 134 to the left. If the oncoming light again cuts off the left-hand triode section to this extent, relay coil 114 can be reenergized by completing a circuit to ground through the diode or right-hand portion, and as long as switch 150 is closed, enough current will be supplied to the relay to maintain it in its left-hand switching position.

It is further to be noted that during the time the system is On automatic control, the conventional foot switch 24 is in its right-hand position, as shown in Figure l, with movable contact arm 22 in engagement with stationary 4 contact 26, and when in this position this arm completes a circuit through lamp 32 as follows: voltage supply line 46, line 26, movable switch arm 22, contact 26, line 30, lamp 32 to ground. Thus, at all times when the automatic system is controlling, the lamp 32 will be illuminated.

If the driver desires to manually dim his lights, he moves the movable arm 22 of the conventional foot switch to the left so that it contacts stationary contact 28, thereby completing an obvious circuit through relay coil 18, which attracts its armature 14 to energize the lower beam filaments. By this action the supply circuit to the indicating lamp 32 is broken and this lamp goes out, indicating that the system is no longer controlled by the automatic or light sensitive control system, but is now controlled only by the conventional foot switch.

In that portion of the system directly associated with the headlights, a conventional fuse or circuit breaker is inserted between the battery and line 46 so that if there are any grounds or short circuits, the fuse will burn out or the circuit breaker will open and thus protect the system. In addition the automatic control portion of the device is protected by fuses 138 and so that if difficulties arise in this portion of the circuit, these fuses will also burn out. It will thus be obvious that we have provided a composite system for both automatically, through a light sensitive control, and manually energizing as desired, the upper or lower beam filaments of multi-filament headlamps, and that when the automatic system is employed, indicating means are energized to advise the operator that this system is in use, and that if this indicating means is not energized the manual system is controlling.

In the modification shown in Figure 2, the pickup unit is shown as a block diagram obtaining power from the potentiometer 74, 76, 78 as before, and whose output line 96 is connected to resistors 98, 102 and potentiometer 104 in series, and also to the control grid 124 of the double triode tube 122, as in Figure 1. The sensitive relay 40', as previously described, operates its armature 134 and the power supply consisting of vibrator 54 and transformer 52 energizes the secondaries 56 and 58 respectively. Overriding switch 150 is again connected through line 146 to the control grid 144 of the second section of the tube 122 and anodes 118 and 120 are both connected through line 116 to relay coil 114 of the relay 40'.

Relay 40 has three stationary contacts 133 and 38 as in the previous case, and an additional contact that is located adjacent contact 133 and is engaged by the armature 134 when in its left-hand position and in engagement with contact 133. Stationary contact 133 is connected through line 132 to line 100. Condenser 130 is connected between line 100 and line 70. Stationary contact 170 is connected to line 36' which extends to relay coil 18. A stationary contact 38 is in this case unconnected electrically and acts merely as a mechanical stop when the armature is pulled away from the coil by the spring 154. The armature 134 is connected to line 162 which extends to stationary contact 26 of the foot switch 24. Stationary contact 28 of the foot switch 24 is unconnected electrically.

In this form of our invention a master switch 172 is provided so that the operator may definitely set the sys tem to operate either on conventional manual foot switch operation or on light controlled automatic operation. This switch is of the single pole double throw type havmg two opposed stationary contacts 174 and 176 and a movable contact 178 which may be moved to engage either one. Tie line 180 connects contact 174 to line 36'. Tie line 182 connects movable contact 178 to line 162. Indicating or pilot lamp 32 is connected between contact 176 and ground. In this Figure 2 the connections to the headlamp filaments are reversed from the showing in Figure l, conductive line 12 being connected to terminal 2 for the upper beam filaments and conductive line 6 connected to terminal 4' for the lower beam filaments. With this system the indicating lamp 32 will be energized whenever swit; hes 24 and 172 are moved to automatic operation position to indicate the same.

When the movable switch arm 178 is moved to engage the stationary contact 174, the system is adapted for manual control by the conventional foot switch 24 and pilot lamp 32 is deenergized. With the foot switch 24 in the position shown in which armature 22 engages contact 26, the following energizing circuit is completed for the relay coil 18: line 46, line 20, armature 22, contact 26, line 162, line 182, movable contact 178, stationary contact 174, line 180, line 36', coil 18 to ground. Thus the armature 14 will be attracted and the upper beam filaments energized, If the conventional foot switch 24- is now manually operated, the armature 22 will move away from contact 26 and engage contact 28, thus breaking the circuit just traced and deenergizing the coil 18. Spring 16 will move the armature 14 to its upper position to break the circuit to the upper beam filaments and energize the lower beam filaments. Thus with the switch 172 in this manual position, alternate operation of the foot switch 24 will energize high and low beam filaments. The indicating light 32 will not be energized for either high or low beam operation as long as switch 172 is in manual position.

When the master switch 172 is moved to automatic operation position so that movable armature 178 engages stationary contact 176, an obvious circuit will be completed to the indicating lamp 32 which will remain lighted as long as the system is in condition for automatic control. The conventional foot switch 24 must be in the position shown and will remain there during automatic operation. Under these conditions and assuming no light falling on the pickup unit, upper or high beam illumination is desired. Sensitive control relay 40 is energized by current flow through the first triode section of the tube 122 and holds its armature 134 to the left, engaging contacts 170 and 133. An energizing circuit is completed for the power relay coil 18 as follows: line 46, line 20, switch arm 22, contact 26, line 162, armature 134, contact 170, line 36, coil 18 to ground. The coil 18 holds its armature 14 in its lower position, thus completing a circuit to the upper beam filaments. The headlamp filament energization is controlled automatically and pilot light 32 is energized.

If a car approaches and sufficient light falls on the pickup unit 160 to reducethe bias on grid 124 to the point where there is insufficient current flow through the tube 122 and the coil 114 in series therewith to maintain the armature 134 in the left-hand position as shown, then spring 154 will move it to the right, opening the previously traced energizing circuit for the coil 18 and the armature 14 actuated thereby will move up through action of spring 16. This will cause the filaments to be switched from high beam to low beam. As long as sufficient light impinges on the pickup unit, the energizing circuit for the power relay coil 18 remains open and the filaments on low beam. The pilot light 32 remains energized as long as switches 24 and 172 are in automatic position.

Figure 3 shows a partial circuit similar to that of Figure 2 in which the master switch 172 is omitted and the pilot light 32 to indicate automatic operation is directly connected to line 162, the other portion of Figure 2 remaining the same. It will be obvious that pilot light 32 will thus be energized at any time that conventional foot switch 24 is moved to the right hand position, as shown in Figure 2, with armature 22 in engagement with stationary contact 26. This is the position in which switch 24 is placed for automatic operation. If this switch is moved so that armature 22 engages contact 28, then the low beam filaments are manually switched and the lamp 32 is deenergized.

It is also'w'ithin the scope of our invention to obtain indications by connecting the signalling means, such for example as an indicating light, to the non-automatic portion of the system so that the indicator will be energized when the system is adjusted for non-automatic operation. One manner in which this might be accomplished would be to connect the pilot lamp 32 to the stationary contact 28 in Figure 3, in which case the lamp would be energized at any time that the conventional foot switch 24 was operated to move the armature 22 to the left for non-automatic operation. In this case the energization of the lamp 32 would then warn the operator that the system is in non-automatic condition.

We claim:

1. In automotive headlamp means having dim and bright filaments, a source of electrical power, light sensitive means connected thereto, amplifying means connected to the light sensitive means, relay switching means connected to the output of the amplifier and to the filaments to switch from one set of filaments to the other, depending upon the amount of light falling on the light sensitive means, manual switching means connected to the source, to the filaments and to the relay switching means, means for indicating whether the automatic light sensitive system or the manual means is in use to control the energization of the filaments, and a master switch connected between the manual switching means and the automatic light sensitive system determining which shall control the filament energization.

2. In automotive headlamp means having dim and bright filaments, a source of electrical power, light sensitive means connected thereto, amplifying means connected to the light sensitive means, relay switching means connected to the output of the amplifier and to the filaments to switch from one set of filaments to the other, depending upon the amount of light falling on the light sensitive means, manual switching means connected to the source, to the filaments and to the relay switching means, a master switch connected across the relay switching means to determine whether manual or automatic switching means shall control, and means for indicating whether the automatic light sensitive system or the manual means is in use to control the energization of the filaments connected directly to the master switch.

3. In automotive headlamp means having dim and bright filaments, a source of power, switching means connected to said source and to said filaments for alternately energizing the same, a relay coil for actuating said switching means, a light sensitive means connected to said source of power, an amplifier connected to the light sensitive means, biasing means for the amplifier, a shunting circuit for a portion of the biasing means, relay switching means connected to the output of the amplifier and actuated by the same, said relay switching means being connected to the shunting circuit and to the relay coil to control the latter and vary the bias on the amplifier, manual switching means connected between the relay switching means and the relay coil to control energization of the same, and indicating means connected to the manual switching means to indicate which control is efiective.

4. In automotive headlamp means having dim and bright filaments, a source of electrical power, switching means connected to the filaments and to the source of power to alternately energize the dim and bright filaments, a relay coil for operating said switching means, a manual switching means having movable means and contacts engageable upon opposite sides thereof connected to the source of power, first-named switching means and to the relay coil, a light controlled switching means connected to the source of power and to the relay coil to control the energization of the relay coil in response to the amount of incident light so that the switching means 8 a is controlled by manual switching means or automati- References Cited inthe file of this patent cally through the light controlled means and energizable UNITED STATES PATENTS indicating means connected directly between one of the manual switch contacts and ground to indicate whether 1,930,497 Wnght 1933 the filament energization is under automatic or manual 5 2150'900 Alley 1939 comwL 2,598,420 Onksen May 27, 1952 

